Local plasmon sensor with gold colloid monolayers deposited upon glass substrates

Abstract

A new optical sensor that uses local plasmon resonance is proposed. A peak that is due to the local plasmon resonance appears in the absorption spectrum of a gold colloid suspension in the visible region, and its height and wavelength depend on the refractive index of the suspension. These properties are used for optical sensors. We used gold colloid monolayers in which colloidal gold particles a few tens of nanometers in diameter were immobilized upon a glass slide by a functional organic coupling agent. We measured the absorption spectra of the the gold colloid monolayers, which were immersed in liquid samples or coated with thin films. We observed increases of both the resonance wavelength and the absorbance as the refractive indices of the sample liquids or the thickness of the coated films increased. The proportional constants of the resonance wavelength to the film thickness were 3.6 and 5.7 for a 13.9- and a 20.2-nm gold colloid monolayer, respectively.

Measurement of the localised plasmon penetration depth for gold nanoparticles using a non-invasive bio-stacking method

“…A comparison of the observed l d, of 90 nm can be made with the reported experimental LSPR sensor response saturations observed for a range of gold particles sizes and shapes. The sensing depth of spherical particles has been determined for a variety of different size particles to be from 24 nm for 12nm particles, 20-25 nm for 15 nm particles, to 40 nm for 39 nm particles 5,19,20 , about 1-2 particle diameters for the studied size range. The plasmon interaction range is also estimated to be the order of the particle diameter for 10, 20, 150 nm diameter particles 8 , which is comparable to our result.…”

High-resolution contrast-enhanced optical coherence tomography in mice retinae

“…First, we observed a shift in the GNR spectral peak (∼830 nm in UV-Vis), which may be attributed to changes in plasmonic property of the GNRs due to high refractive index mounting media 23 and adsorbed proteins on their surface. 24 Even though H&E staining of histological section provides excellent anatomical references for the retinal layers, such staining interfered with the spectral detection of GNRs, leading us to image unstained sections.…”

A localized surface plasmon resonance based immunosensor for the detection of casein in milk

“…The optical characteristics of the LSPR-based sensor using noble metal nanoparticles were reported with the redshift in the peak wavelength [22,35] and the increment of ARTICLE IN PRESS the absorbance intensity [21,24,36] when the thickness of biomolecular layer increased and the refractive index changed due to the reaction between the solution under study and the receptor immobilized on the surface. In our gold-capped nanoparticle substrate, we also observed a significant increase in the absorbance intensity of the LSPR ARTICLE IN PRESS Fig.…”

“…Using a gold nanoparticle monolayer immobilized on the glass substrate, the increments in the intensity of peak absorbance and the red-shift in the peak wavelength of LSPR band were observed, as the refractive index of the sample solution and the thickness of the coated film increased [21]. Furthermore, the optical biosensor based on the measurement of the transmission absorption spectra has been developed, and the effect of various nanoparticle sizes on the sensitivity of the LSPR-based biosensors was also investigated [22,23].…”